Mobile information devices, such as liquid crystal displays, mobile phones, and tablets, and electronic devices, such as digital cameras, organic EL displays, organic EL lighting, and sensors, have been desired not only to be smaller and thinner, but also to offer further higher performance. As a method for manufacturing such electronic devices more inexpensively, printed electronics by which wiring is directly printed has attracted attention.
Thin film transistors and electronic circuits including such transistors are produced by laminating various thin films, such as semiconductors, insulators, and electric conductors, on a substrate and suitably forming a predetermined pattern with photolithography. Photolithography is a technique in which, for example, a circuit pattern formed of a material impervious to light on a transparent flat plate called a photomask is transferred onto a target substrate by making use of light, and the technique has been widely made use of in a process for manufacturing, for example, semiconductor integrated circuits.
Conventional production processes using photolithography require multiple steps, such as exposure, development, baking, and peeling, even only for a mask pattern formed of a photosensitive organic resin material called photoresist. Hence, as the number of photolithographic steps increased, a production cost is also increased. To solve these problems, an attempt of manufacturing a thin film transistor with reducing photolithographic steps has been made.
Furthermore, in recent years, substrates are becoming increasingly larger in area. With this increase, vacuum apparatuses, such as CVD systems, are remarkably becoming huge in size; prices for the apparatuses are remarkably rising; and power consumption is remarkably being increased, and accordingly, production cost tends to increase. Against this background, for example, with the aim of process cost reduction, a non-vacuum process has been attracting attention. The non-vacuum process offers advantages, such as reduction in capital investment and running cost, and simpler maintenance.
The production of electronic components by printing processes allows a multistage process typically including exposure and development and a vacuum process such as vapor deposition to be bypassed, and hence, a much simpler process can be expected.
Printing processes, such as ink-jet printing, screen printing, gravure printing, and gravure offset printing, enable a wiring of a desired pattern to be formed directly on a substrate, and are therefore made use of as a simpler and low-cost process. However, a film-forming material used flows when a wiring of a desired pattern is formed, and as a result, wet-spreading and bleeding of the material, and accordingly there was a limit to what a wiring and electronic devices that have a fine pattern with excellent linearity are produced by such printing processes.